Recommended Trees forPlains Communities of

Eastern ColoradoA Guide for Selecting, Planting, and Caring For Trees

Special thanks to the International Society of Arboriculture forproviding details and drawings for this brochure.

www.colostate.edu/Depts/CSFS

www.coloradotrees.org

www.fs.fed.us

Avoid topping trees. Topping leads to:• Starvation• Shock• Insects and diseases• Weak limbs• Rapid new growth• Tree death• Ugliness• Increased maintenance costs

Trees that have been topped may become hazardous and unsightly.

Do Not Top Your Trees!

Trees to avoid!Selecting the right tree for the right place can help reduce thepotential for catastrophic loss of trees by insects, disease or envi-ronmental factors. We can’t control the weather, but we can usediscernment in selecting trees to plant. A variety of tree speciesshould be planted so no single species represents more than 10-15percent of a community’s total tree population. Many trees are notrecommended because of brittle wood, susceptibility to insects anddiseases, or their ability to spread in to native ecosystems and out-compete native species, while others simply do not grow well inour climate. The following is a list of tree species NOT recom-mended for the Eastern Plains of Colorado:

Species NOT recommended

Austree (Salix alba x matsudana)

Aspen (Populus tremuloides)

Silver maple (Acer saccharinum)

Russian-olive (Elaeagnus angustifolia)

Tree-of-Heaven (Ailanthus altissima)

Mountain-ash (Sorbus aucuparia)

Tamarisk (Tamarix spp.)

Willows (Salix spp.)

Birches (Betula spp.)

Non-native hybrid poplars/cottonwoods (Populus spp.)

Siberian elm (Ulmus pumila)

Tree SelectionTree selection is one of the most important investment decisions ahome owner makes when landscaping a new home or replacing atree lost to damage or disease. Most trees can outlive the peoplewho plant them, therefore the impact of this decision is one thatcan influence a lifetime. Matching the tree to the site is critical; thefollowing site and tree demands should be considered beforebuying and planting a tree.

Site Considerations

• Available space above and below ground

• Water availability

• Drainage

• Soil texture and pH

• Sunlight levels/exposure

• Weather and other environmental factors

Tree Considerations

• Growth rate of the species selected

• Mature size

• Form

• Hardiness – ability of a plant to survive low temperatures

• Heat tolerance and drought tolerance

• Pest resistance

• Maintenance issues

• Native vs. non-native species

pyramidalspreading globefull-crowned columnarvase

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Selecting Trees at the NurseryWhen you buy a high-quality tree, plant it correctly, and treat itproperly, you and your tree will benefit greatly for manyyears.When you buy a low-quality tree, you and your tree will havemany costly problems even if you take great care in planting andmaintenance. Consider the following when selecting a tree at thenursery:

• Tree should appear healthy. No discoloredbark, wilted leaves, etc.

• Branches should be spaced evenly aroundthe trunk

• Tree trunk should taper from a solid base,gradually becoming more slender towardsthe top.

• Tree foliage and branches should be distrib-uted on upper 2/3 of tree.

• Tree should contain a central, dominantleader.

• Tree should be free from mechanicaldamage.

• Tree should be free from insects and diseases.

• Roots should not be girdling, circling or potbound.

Tree Planting Tips• Plant the top of the root ball slightly above ground level. The

root collar (flare) must be visible one inch above final grade.

• Set root ball on solid ground and not on loose backfill in thehole; this will eliminate settling.

• Remove at least the top 1/2 of all wire and baskets from balledand burlapped trees and completely remove containers fromcontainerized stock.

• Adding peat moss or manure to soil in the planting hole is notnecessary. (Too much can cause a “potted tree” effect andrestrict root growth.) Backfill hole with original soil.

Small evergreens(15 - 25 feet mature height)

Piñon* (Pinus edulis)Dense, bushy pine, short grayish-green needles, getting hit hard by Ips beetle inparts of State

Bristlecone pine* (Pinus aristata)Bushy dark green needles, very slow growing

Eastern red cedar* (Juniperus virginiana)Very hardy tree, excellent windbreak tree, green summer foliage, rusty brown inthe winter

Junipers, upright* (Juniperus scopulorum)Very hardy tree, excellent windbreak tree (includes Rocky Mountain juniper)

Basaltrunkflare

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• Do not fertilize at planting time.

• Optimum planting periods are from March 15 to June 15 andfrom September 1 to October 15.

• Use mulch 3–4 inches deep, pull back 6 inches from the trunkof the tree, and extend the mulch ring one foot beyond the rootball. This will protect roots, hold soil moisture, reduce weedgrowth, and provide a protective strip to eliminate mechanicaldamage from lawnmowers and weedeaters. Porous landscapecloth may be placed between the soil and the mulch. Do notuse plastic. Keep grass and weeds out of mulched area as theycompete for the same resources as your new tree.

Serviceberry* (Amelanchier spp.)Small trees or large shrubs with showy white flowers and edible fruits

Gambel (scrub) oak* (Quercus gambelii)Native acorn-producing oak with great variability in size and shape

Japanese tree lilac* (Syringa reticulata)Creamy, white flower clusters with showy, dark bark

Large Evergreens(30 - 60 feet mature height)Do not use as street trees!

Colorado blue spruce* (Picea pungens)State tree, sharp stiff needles, color of needles rangefrom bright green to silver blue

Austrian pine* (Pinus nigra)Long needle pine, works well in a windbreak

Concolor (white) fir (Abies concolor)Long soft blue-green needles, plant in a protected site,shade tolerant

Scots pine* (Pinus sylvestris)Short needle pine, orange bark with age

Ponderosa pine* (Pinus ponderosa)Long needle pine, native to Colorado, hardy tree

Cut burlap and ropeaway from top halfof root ball

Set ball on firmlypacked soil toprevent settling

Gently pack back-fill usingwater to settle soil aroundroot ball

Keep mulch 6"back from trunk

Use two opposingflexible ties whenstaking is necessary

3-4" layerof mulch Trunk

flare

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White fir

Ponderosapine

Coloradoblue spruce

• If necessary, stake tree properly to keep root ball from shifting.Main tree stem must be able to sway slightly; if it is too rigid,root growth, diameter of stem, and height growth will beadversely affected.

• Use wide straps for tying trees to stakes. Do not use wire,string, rope, or rubber hose around tree.

• Remove stakes and straps after roots are established, usuallyone or two growing seasons.

• Keep soil moist but not saturated.

Tree WateringThe correct amount of water is the most important factor in ensur-ing proper tree establishment. Too much water can be as damagingto a newly planted tree as too little water, so be sure to periodicallycheck soil moisture by examining the soil in the area of the roots.Follow these recommendations to help your tree establish in thelandscape:

• Water deeply and slowly. Apply water so it moistens thecritical root zone (from near the trunk of the tree to thedripline) to a depth of twelve inches. Methods for wateringinclude a deep root fork or needle, soaker hose or soft spraywand. Apply water to many locations under the dripline. If adeep root fork or needle is used, insert the device no deeperthan eight inches into the soil.

• Consistent moisture is essential. Maintaining consistent soilmoisture allows for better root water absorption. Droughtstressed or over-watered trees are more vulnerable to diseaseand insect infestations, as well as branch dieback.

• When should I water? Generally, water a newly planted treeevery 3-5 days during the growing season, depending onweather and soil conditions. Remember that newly plantedtrees need water during dry periods in the winter months aswell. Try to water at least once a month in the dormant season.

Japanese Pagodatree* (Sophora japonica)Rounded crown, olive green bark, abundant white flowers

Ohio Buckeye* (Aesculus glabra)Very similar to horsechestnut with a bit smaller leavesthat can occasionally scorch

Amur corktree* (Phellodendron amurense)Round broad spreading tree, bark is cork like, leaves darkgreen on top and light green on bottom

Mayday tree (Prunus padus)White flowers, black drupe fruit, yellow to orange fall color

Ussurian pear* (Pyrus ussuriensis)White flowers, small fruit, red wine fall color

Canyon maple* (Acer grandidentatum)Slow growing, Rocky Mountain native, shades of yellow, orangeand red in fall

Small Ornamental Trees(<25 feet mature height)

Hawthorn species* (Crataegus spp.)Flowers in the spring, small fruit produced, most varieties contain small thorns

Crabapple species* (Malus spp.)Flowers in the spring, most varieties produce fruit, select a variety that has ahigh resistance to fire blight

Amur Maple* (Acer ginnala)Yellow- white flowers, abundant seed, orange to red fall color

Tatarian Maple* (Acer tataricum)Winged seeds good for birds, fall color orange-red, hardy tree

Sumac* (Rhus typhina or R. glabra)Bright red fall color, spreads aggressively by suckers

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Ohio buckeye

Ussurianpear

• How much water should I apply? Utilize the following “ruleof thumb” for watering: apply 10 gallons of water per inch oftree diameter, for instance a 1 inch tree will require 10 gallonsof water each time it is watered. For mature trees 10 inches indiameter or more, apply 15 gallons of water per inch of treediameter. Use a ruler to measure your tree’s diameter.

• Mulch helps conserve soil moisture. Mulch is critical toconserve soil moisture. Apply organic mulch within thedripline, at a depth of three to four inches. It’s best to eliminateturf prior to adding mulch. Leave a six-inch space between themulch and trunk of trees. Mulch materials may include woodchips, bark, leaves and evergreen needles.

Tree PruningLimit pruning of newly planted trees to corrective pruning. Re-move torn or broken branches (save other pruning measures for thesecond or third year). Once the tree hasestablished a good root system after plant-ing (usually within 1 to 3 years), properpruning is essential in developing a treewith a strong structure and desirable form.Trees that receive the appropriate pruningmeasures while they are young will requirelittle corrective pruning when they mature.

Location of a pruning cut is critical toa tree’s response in growth and woundclosure. Pruning cuts should be madejust outside the branch collar. Since the branch collar containstrunk or parent branch tissues, the tree will be damaged unneces-sarily if you remove or damage it. In fact, if the cut is large, the treemay suffer permanent internal decay from an improper pruning cut.

For most young trees, maintain a single dominant leader. Do notprune back the tip of this leader. Do not allow secondary branchesto outgrow the leader. Sometimes a tree will develop doubleleaders known as co-dominant stems. These can lead to structuralweaknesses, so it is best to remove one while the tree is young. A

American linden (Tilia americana)Excellent street tree, dark green leaves, yellow-greenfall color

Black walnut*(Juglans nigra)Edible nuts, great for squirrels and birds,nuts may create a mess

Northern catalpa* (Catalpa speciosa)Fragrant white flowers, pencil sized seedpods,large heart shaped leaves

Norway maple (Acer platanoides)Shapely tree, leaf color varies with variety,protect from sun scald

Medium Shade Trees(30 - 45 feet mature height)

Littleleaf linden (Tilia cordata)Yellow flower clusters, pea sized fruit, formalpyramidal form, excellent street tree

Canada red cherry* (Prunus virginiana ‘Shubert’)White flowers, small fruit, new growth on plant is brightgreen and turns maroon, suckers

Horsechestnut* (Aesculus hippocastanum)Greenish-yellow flowers, prickly seed pod,yellow to orange fall color

Golden Raintree* (Koelreuteria paniculata)Yellow flowers in summer, papery pods, leaves redand turn green

Branch Collarpruning cuts should be madejust outside the branch collar

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Norway maple

Northern catalpa

Black walnut

Littleleaflinden

Horsechestnut

good structure of primary scaffold branches should be establishedwhile the tree is young. The scaffold branches provide the frame-work of the mature tree. Properly trained young trees will developa strong structure that will require less corrective pruning as theymature. The goal in training young trees is to establish a strongtrunk with sturdy well-spaced branches.

Need Help?This booklet does not provide all information, on all trees, for alllocations. Each tree species has its own particular needs. TheColorado Tree Coalition strongly urges you to contact your localtree expert for more information, please call your:

• Community tree board

• City Forester

• City’s Parks Department

• Arborist

• Forestry Consultant

• Tree Nursery

• Colorado State University Cooperative Extension

• Colorado State Forest Service District Office

Recommended Trees for PlainsCommunities of Eastern Colorado

*Signifies trees that can withstand drier conditions

Large Shade Trees(>50 feet mature height)

English oak* (Quercus robur)Produces acorns, rounded crown, dark green leaves turnbrown and remain on tree through winter

Hackberry* (Celtis occidentalis)Very hardy, can be susceptible to nipple gall, a cosmeticinjury, reddish purple cherry like berries

Bur oak* (Quercus macrocarpa)Produces acorns, fall color yellow to brown andoccasionally red, very hardy and long lived

Honeylocust* (Gleditsia triacanthos inermis)Hardy trees, dark green, fern-like leaves, yellow fall color

Swamp white oak (Quercus bicolor)Produces acorns, deep green leaves white underneath

Kentucky coffeetree* (Gymnocladus dioica)Fragrant white flowers, persistent seed pods produced,large shade tree

American elm (Ulmus americana)Disease-resistant hybrids can be very hardy, broad shapedcrown, excellent street tree

Ginkgo (Ginkgo biloba)Few insect and disease problems, pretty fall color, distinctive leaf shape

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Kentuckycoffeetree

Honeylocust

Hackberry